The present invention relates to a method for reserved-recording broadcast programs in a recorder and an apparatus therefor, and more particularly, to a method for recording a plurality of broadcast programs which are reserved for a certain period of time, within the limit of capacity of a recording medium, and an apparatus therefor.
There are a general recording method and a reserved-recording method for recording a television broadcast program (hereinafter, referred to as a "program"). The general recording method records on a recording medium programs of a current reception channel according to a user selecting a recording mode. Meanwhile, in the reserved recording method, if a user presets information including a channel number, a recording start time, a recording end time and a recording speed of a program to be recorded, a video cassette recorder (VCR) detects the recording start time of the reserved program to automatically record the corresponding program, and detects the recording end time during recording to finish the recording operation. In the recording methods, a recording speed mode representative of a running speed of a tape includes a standardized SP (standard play) mode, a LP (long play) mode having half the tape speed of the SP mode, a SLP (super long play) mode having one third tape speed of the SP mode, and an AUTO (automatic play) mode allowing the system to select the tape recording speed automatically.
A conventional reserved recording method will be described below with reference to FIGS. 1A, 1B and 2. Referring to FIG. 1A, a user reserved-records in a SP mode a program which is broadcasted via channel 6 from 10 a.m. to 12 a.m. on January 15. Also, referring to FIG. 1B, a user reserved-records in a SLP mode a program which is broadcasted via channel 6 from 09 a.m. to 12 a.m. on January 15. As such, the user compares the reserved-recording time of the program with a remaining time of tape and then manually sets the recording speed such as a SP mode or a SLP mode, in the prior art. Such a method may cause inconveniences because the user must calculate the reserved-recording time and the tape remaining time and always set a corresponding recording speed based on calculation result.
To solve the above problem, there has been a method for setting a recording speed mode to an AUTO mode by a user. There are two types of methods for setting a method for recording a reserved program in an AUTO mode in a VCR. One is a method for comparing a reserved-recording time and a tape remaining time with each other, to then determine a recording speed when a VCR starts a reserved-recording. If the reserved-recording time is equal to or shorter than the tape remaining time, the VCR records the program in a SP mode from the beginning, while if the former is longer than the latter, the VCR records the program in a SLP mode from the beginning. In this method, assuming that the tape remaining time of a tape cassette loaded into the VCR is 120 minutes, if a reserved-recording time of the program is 180 minutes as in an example of FIG. 2 where the program is set in an AUTO mode, the reserved-recording time is longer than the tape remaining time. Accordingly, the VCR selects the SLP mode from the recording start time to thereby record the program of 180 minutes on the 60-minute capacity of tape, and leaves the remaining 60-minute tape time to then finish the recording operation. In this case, since the VCR records the program in the SLP mode from the recording start time, there is a drawback that picture quality of the recorded program is deteriorated compared with the case when the program are recorded in the SP mode.
The other method to solve the problem is called a just-recording method, in which the reserved-recording remaining time and the tape remaining time are continuously checked and compared with each other from the recording start point of time, and the program is recorded in the SP mode whose picture quality if better than that of the SLP mode up to an appropriate point of time, and thereafter the programs are recorded in the SLP mode so as not to leave the tape remaining time. Specifically, when it reaches the recording start point in time of the reserved program, a system controller of the VCR calculates a tape remaining time according to a reel state detect signal and a just-recording time according to the following equation (1), respectively, and compares the two values. If the just-recording time is shorter than the tape remaining time, the system controller controls the receives program to be recorded in the SP mode. If the just-recording time is equal to or longer than the tape remaining time during recording of the reserved program, the system controller controls the received program to be recorded in the changed SLP mode. ##EQU1##
Here, J represents a just-recording time, R represents the reserved-recording remaining time of a corresponding program, and T represents a tape remaining time. In other words, the reserved-recording remaining time of the corresponding program is obtained by subtracting a current time of the system from a recording end time of the reserved program, and the tape remaining time is calculated as a recordable remaining time of the tape wound on a supply reel in the standard recording speed mode (SP) by analyzing a signal detected from a reel status detector under the control of the system controller.
As an explanation example, it is assumed that user reserves a program to be recorded as shown in FIG. 2, and a 120-minute tape cassette is loaded into a VCR and rewound to the beginning state. If it becomes 9 a.m. on January 15, the timer in the VCR detects the time and informs the system controller that it has reached the reserved recording start time. The system controller reads information on the reserved program from a memory, receives current time information from the timer to calculate a reserved-recording remaining time of the corresponding program, and analyzes the signals from the reel status detector for detecting the states of a supply reel and a take-up reel to calculate the remaining time of the tape. As a result of calculation, since the reserved-recording remaining time of the program is 180 minutes and the tape remaining time is 120 minutes at the point of time when the recording of the program starts, the just-recording time becomes 30 minutes corresponding to (180 minutes-120 minutes)/2 according to the above equation (1). Thus, since the just-recording time is shorter by 90 minutes than the tape remaining time, the system controller controls the corresponding program to be recorded in the SP mode at the beginning. Thereafter, the tape remaining time and the just-recording time are continuously calculated and compared with each other, and thus it is compared whether the just-recording time matches the tape remaining time. If 90 minutes passes while the above process is repeated continuously, the reserved-recording remaining time of the program becomes 90 minutes, the tape remaining time does 30 minutes, and the just-recording time does 30 minutes in the result of calculation of (90-30)/2 according to the above equation (1). Thus, since the just-recording time matches the tape remaining time, the system controller changes the recording speed into the SLP mode, to then record the corresponding program of 90-minute length for the remaining 30 minutes. As a result, the reserved-recording apparatus adopting the just-recording method records, at maximum, the program in the SP mode whose picture quality is better than that of the SLP mode, and then records the remaining of the program in the SLP mode on the remaining length of the tape.
However, the conventional reserved-recording method adopting the above just-recording method operates only in units of a single program. In more detail, although a plurality of programs are set for reserved recording, the conventional reserved-recording method calculates the just-recording time in units of a single program as expressed in the equation (1), and compares the calculated just-recording time with the tape remaining time, to change the recording speed of the program at an appropriate point in time. Thus, if the reserved-recording time of the firstly reserved program is longer than the tape remaining time, the tape remaining time is insufficient. As a result, a VCR may not record the subsequently reserved programs, which will be described with reference to FIG. 3.
FIG. 3 shows a state where three programs are reserved in the AUTO mode. It is assumed that a user reservation-sets desired programs as shown in FIG. 3, a 120-minute tape cassette is loaded into a VCR and rewound up to the beginning state. In this case, if the VCR performs a reservation recording by use of the conventional just-recording method as shown in an explanation example of FIG. 2, the first program shown in FIG. 3 can be recorded, and the following programs cannot be recorded at all since the tape remaining time is insufficient. Here, if the user wishes to record all the program subsequently to the second program, the conventional reserved-recording method cannot meet the user desire.